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AGENCY OF MICRO-ORGANISMS IN CARIES. 751
From time to time durino; the discussion of the relations of micro-
organisms to the process of lermentation there have appeared suggestions
that decay of the teeth might be a result of the action of microbes. But
the first extended study of fungi in connection with this process was
undertaken by Leber and Rottenstein, who published an account of
their observations in 1867.' At the time their studies were made plans
for the separation and individual study of those micro-organisms which
appear in conne(;tion with the carious process had not been systematized.
Hence these observers seem to have confounded all other micro-organ-
isms with Leptothrix buccalis. By treating decayed dentine with iodine
and acids a violet color of the granular masses filling the widened
tubules was obtained, and the conclusion that these were composed,
in part at least, of micro-organisms was announced—an observation
since confirmed by the use of the improved methods of staining intro-
duced by Dr. Koch. So complete has this demonstration been that in
any case of erosive softening of tooth-structure within M'hich micro-
organisms cannot be demonstrated by well-known processes we are
justified in saying that such a softening is not true caries, or is not of
the nature of caries as it is found in the human mouth. Leber and Rot-
tenstein do not regard the fungus as capable of penetrating the normal
enamel or dentine, but suppose that, a beginning being made by an acid,
it enters, and by its growth assists in the destructive process.
The following extracts define the views of these authors upon this
point (pp. 68-97)
" From what has been said, it results that two principal phenomena man-
ifest themselves in the formation of dental caries—viz. the action of acids,
and the rapid development of a parasitic plant, the Leptothrix bucccdis." ....
" It seems that the fungi are not able to penetrate an enamel of normal con-
sistency. The dentine itself, in its normal condition of densitv, offers great
difficulties to their entrance, and we are not yet sure that the leptothrix
could triumph over this resistance." . . . . " We cannot decide at present if
the leptothrix is able to penetrate sound dentine when from any circum-
stance it happens to be denuded." . . . . " But if the enamel or dentine
become less resistant at any point through the action of acids, or if at the
surfiice of the dentine a loss of substance has occurred, then the elements
of the fungus can pass into the interior of the dental tissues, and produce
by their distension, especially of the dentine, effects of softening and destruc-
tion niuch more rapid than the action of acids alone is able to accomplish."
. " The participation of the fungus
. . . is constant in the production of
caries which has reached this stage. As soon as a loss of substance can be
shown there is found the presence of fungus, so that the question whether
or no acids alone could produce ravages more considerable is without
importance."
The modus operandi by M-hich Leptothrix buccalis (or other micro-
organisms) may produce softening of the dentine is left without expla-
nation. It may here be mentioned that in the very beginning of this
line of investigation a mistaken idea was entei'tained, which has been
perpetuated in nearly all subsequent writings upon the subject—that if
micro-organisms are instrumental in the production of decay they must
^An English translation appeared in 1868.
AGENCY OF MICRO-ORGANISMS IN CARIES. 751
From time to time durino; the discussion of the relations of micro-
organisms to the process of lermentation there have appeared suggestions
that decay of the teeth might be a result of the action of microbes. But
the first extended study of fungi in connection with this process was
undertaken by Leber and Rottenstein, who published an account of
their observations in 1867.' At the time their studies were made plans
for the separation and individual study of those micro-organisms which
appear in conne(;tion with the carious process had not been systematized.
Hence these observers seem to have confounded all other micro-organ-
isms with Leptothrix buccalis. By treating decayed dentine with iodine
and acids a violet color of the granular masses filling the widened
tubules was obtained, and the conclusion that these were composed,
in part at least, of micro-organisms was announced—an observation
since confirmed by the use of the improved methods of staining intro-
duced by Dr. Koch. So complete has this demonstration been that in
any case of erosive softening of tooth-structure within M'hich micro-
organisms cannot be demonstrated by well-known processes we are
justified in saying that such a softening is not true caries, or is not of
the nature of caries as it is found in the human mouth. Leber and Rot-
tenstein do not regard the fungus as capable of penetrating the normal
enamel or dentine, but suppose that, a beginning being made by an acid,
it enters, and by its growth assists in the destructive process.
The following extracts define the views of these authors upon this
point (pp. 68-97)
" From what has been said, it results that two principal phenomena man-
ifest themselves in the formation of dental caries—viz. the action of acids,
and the rapid development of a parasitic plant, the Leptothrix bucccdis." ....
" It seems that the fungi are not able to penetrate an enamel of normal con-
sistency. The dentine itself, in its normal condition of densitv, offers great
difficulties to their entrance, and we are not yet sure that the leptothrix
could triumph over this resistance." . . . . " We cannot decide at present if
the leptothrix is able to penetrate sound dentine when from any circum-
stance it happens to be denuded." . . . . " But if the enamel or dentine
become less resistant at any point through the action of acids, or if at the
surfiice of the dentine a loss of substance has occurred, then the elements
of the fungus can pass into the interior of the dental tissues, and produce
by their distension, especially of the dentine, effects of softening and destruc-
tion niuch more rapid than the action of acids alone is able to accomplish."
. " The participation of the fungus
. . . is constant in the production of
caries which has reached this stage. As soon as a loss of substance can be
shown there is found the presence of fungus, so that the question whether
or no acids alone could produce ravages more considerable is without
importance."
The modus operandi by M-hich Leptothrix buccalis (or other micro-
organisms) may produce softening of the dentine is left without expla-
nation. It may here be mentioned that in the very beginning of this
line of investigation a mistaken idea was entei'tained, which has been
perpetuated in nearly all subsequent writings upon the subject—that if
micro-organisms are instrumental in the production of decay they must
^An English translation appeared in 1868.
